The present invention relates to a device for launching and recovering an underwater vehicle.
The operation of submerging an underwater vehicle several meters under the surface of the sea, from a platform of a boat is made tricky by the vertical movements of the boat which are caused on the surface of the water by the swell, and are conventionally known as xe2x80x9cheavexe2x80x9d. The vertical movements due to the swell at a depth of a few meters are attenuated but since the launch and recovery device is generally fixed to the boat by means of a cable, it is driven vertically by the boat. The relative movements of the underwater vehicle and of the launch and recovery device may cause damage to the said underwater vehicle.
Document U.S. Pat. No. 3,807,335 discloses a submerged platform intended for submerging an underwater vehicle fixed vertically under the platform which is secured to a boat by cables connected to the platform via dampers, so as to attenuate the vertical movements of the platform which are due to the vertical movements of the boat.
Nonetheless, this device for launching and recovering an underwater vehicle does not make it possible to completely get around the problem of the vertical movements, which can merely be attenuated.
The invention proposes a device for launching and recovering an underwater vehicle which makes it possible to get around the disadvantages associated with the heave.
The invention also proposes a device for launching and recovering an underwater vehicle which is suited to the storage of the underwater vehicle on a boat.
The invention finally proposes a device which allows an underwater vehicle to be launched and recovered near to its working depth.
A device for launching and recovering an underwater vehicle according to the invention comprises a submersible assembly comprising a lower chassis and an upper chassis, the lower and upper chassis being connected by a flexible connection, so that the distance between the said upper and lower chassis is adjustable to make it easier for the underwater vehicle to move in a zone lying between the lower and upper chassis.
The flexible connection and the lower and upper chassis form a receiving cage provided with an opening 28, the vertical dimension of which can be adjusted. Moving the lower and upper chassis apart makes it possible to enlarge the vertical dimension of the said opening so that the underwater vehicle can enter or leave the cage without the movements of the cage due to the heave impeding the entry or departure of the underwater vehicle. Moving the lower and upper chassis closer together in the vertical direction makes it possible, in spite of the vertical movements of the cage as a whole as a result of the heave, to support the underwater vehicle on the lower chassis and hold it in place using the upper chassis. By moving the lower and upper chassis closer together quickly enough, successive impacts between the underwater vehicle and the lower chassis are avoided.
In one embodiment, the lower and upper chassis are connected by a cable bundle, the cables of which can easily be wound onto pulleys so as to reduce the distance between the lower and upper chassis, or unwound so as to increase the distance between the lower and upper chassis.
In one embodiment, the launch and recovery device comprises means of winding up and unwinding the cables, which allows the length of the cables and therefore the separation between the lower chassis and the upper chassis to be adjusted.
In one embodiment, the device comprises at least one motor used to rotate a number of pulleys onto which the flexible connection is wound.
As a preference, the device is secured to a boat situated at the surface by at least one cable of adjustable length. Thus, the submersible assembly can be submerged to the desired depth, for example a depth close to the working depth of the underwater vehicle.
Advantageously, positioning means are arranged between the upper chassis and the lower chassis. The positioning means, in the form of stops for example, vertically limit the closeness of the lower and upper chassis so as not to damage the underwater vehicle when the said vehicle is being recovered. The positioning means guide the positioning of the lower chassis with respect to the upper chassis in a horizontal plane so as to make sure that the underwater vehicle is held correctly in the launch and recovery device.
In one embodiment, the lower chassis comprises a lower cradle for receiving the underwater vehicle. The receiving cradle makes recovering the underwater vehicle onto the lower chassis easier.
As a preference, the cradle comprises at least one receiving concave wall, the profile of which guides the underwater vehicle as contact is made between the lower chassis and the underwater vehicle while the said underwater vehicle is being recovered.
Advantageously, the cradle can be detached from the lower chassis. Thus, when the device is returned, with the underwater vehicle, to the device situated at the surface, it is possible easily to access the underwater vehicle, for example for maintenance operations, by moving away the cage formed by the launch and recovery device so as to gain access to the underwater vehicle.
In one embodiment, the upper chassis comprises an upper holding cradle, which allows the underwater vehicle to be held in place in the launch and recovery device.
The invention also relates to a method for launching and recovering an underwater vehicle, in which method a launch and recovery device comprising an upper chassis and a lower chassis is submerged, the upper and lower chassis being connected by a flexible connection, so that the distance between the said upper and lower chassis is adjustable, and in which device an underwater vehicle is placed. The distance between the upper and lower chassis is increased to release the underwater vehicle, and the distance between the upper and lower chassis is reduced for recovering the underwater vehicle once the underwater vehicle has moved into a zone lying between the lower and upper chassis.